MATERIALS FOR A MONOGRAPH OF THK ASCONS. 489 



mordialis, Leiidenfeld took the singular view that the cells in 

 question were the mother-cells of the choanocytes, apparently 

 for the sole reason that they were continuous with some sort of 

 coagulum which appeared in his preparations between the 

 collar-cells. Indeed, although I formerly believed that von 

 Lendeufeld's supposed " Kragenmutterzellen " were in reality 

 the closed pores, I should be more inclined now to regard them 

 simply as parts of the coagulum which he figures, had he not 

 more recently (1894 [2], p. 508) asserted definitely that the 

 cells which Bidder and myself identify as closed pores are the 

 same as those which he regai'ds as the mother-cells of the 

 choanocytes. In that case the statement which he twice 

 repeats (1891, p. 201, and 1894 [2], p. 508), that the proto- 

 plasm of these cells agrees in its characters with that of the 

 collar-cells, is absolutely astounding, even to those who are 

 acquainted with his writings on sponge histology; for if there 

 are in the sponge body, cells which differ more than others, in 

 every character in which cells can differ, from the collar-cells, 

 it is the porocytes (compare my PI. 41, fig. 39). Looking 

 again at his figures, I am inclined to think that in spinosa 

 (1. c, fig. 22, a) he has represented true porocytes, which he 

 identifies as symbiotic vegetable bodies, but that the structures 

 which in primordialis he has figured as '^ Kragenmutter- 

 zellen " (1. c, fig. 23) are simply broken-down cell remnants 

 in a very badly preserved preparation. The question is, in fact, 

 impossible to decide, for it is enough to glance at the figures 

 to which reference has been made to see that they are utterly 

 untrue to nature, and represent, if anything, the cell elements 

 in an advanced stage of putrescence and disintegration. It is 

 nothing short of ludicrous that such figures, and others in the 

 same memoir (figs. 34 — 37, for instance, showing myriads of 

 absolutely non-existent connective- tissue cells) should ever 

 have appeared in a serious scientific journal as representing 

 the histology of these sponges; ^'histology" of this kind would 

 certainly not pass muster in any other group of animals. I 

 think, therefore, that it would be an entire waste of time to 

 ?ittempt to di>cuss further what von Lendenfeld may or may 



